Malaysian officials now believe that missing Malaysia Airlines flight 370 may have been deliberately turned towards the Indian Ocean by someone with up-to-date knowledge of flying and radar positions, a senior military official told AFP Saturday.
The comments lend credence to growing suspicions that the plane, which disappeared a week ago with 239 passengers and crew, might have been commandeered.
"It has to be a skilled, competent and a current pilot," said the official, who is involved in a vast international search and rescue operation and spoke on condition of anonymity.
He said that theory was based on still undisclosed data from military radar.
The radar continued to plot the jet's course for hours after it vanished from air-traffic control screens and civilian radar, he said.
The plane flew in the direction of the Indian Ocean far west of its intended flight path "for four to five hours," the official said.
"He knew how to avoid the civilian radar. He appears to have studied how to avoid it."
Malaysia's air force has previously said that it was investigating an unidentified object spotted by military radar data heading toward the Andaman Sea in the hours after the passenger plane went missing around 1:30 am.
The official would not divulge details of the military data, citing an ongoing investigation.
The Boeing 777 vanished early Saturday on an overnight flight over the South China Sea with no indication of distress, on a clear night.
The plane has one of the best safety records of any jet, and the airline also has a solid record.
The mystery and lack of conclusive evidence so far has spawned a range of theories over what happened, including a mid-air explosion, hijacking, a technical or structural problem, or pilot suicide.
But reports citing various US and other officials involved in the investigation into the plane's mysterious disappearance have increasingly pointed to the possibility that someone with expert flying knowledge diverted the aircraft for unknown reasons.
An international search effort that now involves more than a dozen countries and dozens of ships and aircraft focused initially on waters between Malaysia and Vietnam over which contact with the airliner was lost.
But the failure to find any trace of the plane has seen the search radius continually expanded, now taking Malaysia's west coast and further into the Indian Ocean.